HOUSTON, Texas (KTRK) -- Angel Morales loved to spend time with his family. His cousin says he was doing just that when he was shot and killed at a neighborhood block party on Sunday night.

"He went out the door expecting to have a good time. It went badly, nobody expected a shooting to happen," said Katherine Morales, Angel's cousin.

The shootout happened around 6:37 p.m. in the 4500 block of Yale Street near Crosstimbers Street. Morales' family said he went to the party to watch a band perform.

Dozens of families were at the party. Kids were jumping in an inflatable bounce house and people were enjoying live music.

Witnesses reported hearing dozens of shots fired. Six people were injured by gunfire, but 13-year-old Angel's wounds were fatal.

"He was just innocent. He was a little boy, like every other kid there," Katherine said.

Angel's mother, Olga Valeriano, was devastated.

"I cannot handle it anymore. he was just a kid," Olga said.

Investigators returned to the scene Monday. Police say there were at least two shooters and that it may involve gang members.

"Sadly, we saw last night, people, when they have disagreement, especially potential gang members, that they are quite frankly cowards, if you ask me," said Houston Police Department Chief Art Acevedo.

Police told Eyewitness News they have a possible person of interest in custody.

"I feel like it's really disrespectful. They knew that there were a lot of kids there, and he was the only one that came out dead," Katherine said.

"I want justice, justice for my son. I want the people to come forward. He was only 13 years old," Olga said.

"The gunshots just kept going. I rolled under my girlfriend's car with my kids and we just sat there," Jeffrey said. "If something would have happened to them, I would have died."

Witnesses told police someone tried getting into the party, but security there said they had to be frisked, and that person refused and left.

Shortly after, someone showed up and fired 15 to 20 shots. Investigators are not sure if it's the same person who left the party, refusing to be searched.

A woman, who didn't want to show her face on-camera, says she held Morales' hand while he took his last breaths.

"I don't know if he was trying to say something, but he just kept spitting. I was just trying to keep him alive until the ambulance got here," she said.

A 13-year-old girl was grazed by a bullet, and another person was shot in the leg. Additionally, two juvenile females have wounds from flying glass.

Authorities say the 13-year-old who was grazed by a bullet stayed at the scene to talk to detectives.

A car carrying the other five people went to Doctor's Hospital. All six of the injured are expected to be OK.

"It sounds to me the organizers had it thought through," Houston Police Commander Dan Harris said. "Had security here. It sounds to me like this was something for kids and their parents to come to. There were parents here as well. It just got out of control, which is unfortunate. We can't control the actions of every single person."